v2ex-532105.rb

input = [
  [1,2,3],
  [2,3],
  [3,5],
  [10,15]
]

# 二级引用
class Ref
  attr_accessor :obj
  def initialize(obj)
    @obj = obj
  end
end

def group(input)
  dict = {}
  input.each do |row|
    # 定义一个指向集合的二级引用
    ref = Ref.new(row)
    overlapping = [ref]
    row.each do |value|
      if dict[value]
        overlapping << dict[value]
      else
        dict[value] = ref
      end
    end
    next if overlapping == 1
    # 多个集合需要合并
    new_set = overlapping.uniq.map(&:obj).reduce(&:+).uniq
    overlapping.each {|ref| ref.obj = new_set}
  end
  # 对象去重输出
  dict.values.map(&:obj).uniq
end

p group(input)
#=> [[3, 5, 2, 1], [10, 15]]